Pathobiology of the highly pathogenic avian influenza viruses H7N1 and H5N8 in different chicken breeds and role of Mx 2032 G/A polymorphism in infection outcome

Raúl Sánchez-González,Albert Perlas,Antonio Ramis,Nabil Wali,Rosa Valle,Miquel Nofrarías,Natàlia Majó,Mónica Pérez

doi:10.1186/s13567-020-00835-4

Raúl Sánchez-González, Albert Perlas + Show 6 more

Open Access

https://doi.org/10.1186/s13567-020-00835-4

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Abstract

Chickens are highly susceptible to highly pathogenic avian influenza viruses (HPAIVs). However, the severity of infection varies depending of the viral strain and the genetic background of the host. In this study, we evaluated the pathogenesis of two HPAIVs (H7N1 and H5N8) and assessed the susceptibility to the infection of local and commercial chicken breeds from Spain. Eight chicken breeds were intranasally inoculated with 105 ELD50 of A/Chicken/Italy/5093/1999 (H7N1) or A/Goose/Spain/IA17CR02699/2017 (H5N8 clade 2.3.4.4. B) and monitored during 10 days. Chickens were highly susceptible to both HPAIVs, but H7N1 was considerably more virulent than H5N8 as demonstrated by the highest mortality rates and shortest mean death times (MDT). Both HPAIVs produced severe necrosis and intense viral replication in the central nervous system, heart and pancreas; however, the lesions and replication in other tissues were virus-dependent. High levels of viral RNA were detected by the oral route with both viruses. In contrast, a low number of H5N8-inoculated chickens shed by the cloacal route, demonstrating a different pattern of viral shedding dependent of the HPAIV. We found a high variation in the susceptibility to HPAIVs between the different chicken breeds. The birds carrying the genotype AA and AG at position 2032 in chicken Mx gene presented a slightly higher, but not significant, percentage of survival and a statistically significant longer MDT than GG individuals. Our study demonstrated that the severity of HPAI infection is largely dependent of the viral isolate and host factors, underlining the complexity of HPAI infections.

Highlights

Chickens are highly susceptible to highly pathogenic avian influenza viruses (HPAIVs); the severity of infection varies depending on the viral strain
Clinical signs and mortality The mortality and percentage of clinical signs after experimental infection with either H7N1 or H5N8 HPAIVs in the different chicken breeds are presented in Figure 1 and Table 1
In order to evaluate the existence of viral-and host-dependent differences in HPAIV infections in chickens, we selected a classical HPAIV (H7N1 isolated from a chicken in Italy) and a recent HPAIV of the Gs/GD H5 lineage (H5N8 Gs/GD clade 2.3.4.4 group B isolated from a domestic goose in Spain) and assessed their pathobiology in a broad spectrum of chicken breeds from Spain

Summary

Introduction

Chickens are highly susceptible to highly pathogenic avian influenza viruses (HPAIVs); the severity of infection varies depending on the viral strain. Some HPAIVs produce a peracute infection that kills birds in a shorter period of time (within 3 dpi) [1, 2]. Despite Europe has been affected by the four waves of Gs/GD H5 lineage, the one caused by H5N8 B HPAIV was the largest in magnitude (reported poultry outbreaks and deaths), geographic spread and rapidity of incidents [4, 5]. Since Gs/GD H5N8 B HPAIVs may present altered biological properties in chickens, the pathobiological evaluation of this new viral strain is needed

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